US 2004/0005267 A1 discloses a method for making low sodium lithium carbonate from lithium containing brine. In the method a mother liquor containing carbonate from a prior precipitation step is added to brine to precipitate magnesium as magnesium carbonate; a solution of CaO and sodium carbonate is added to remove calcium and residual magnesium; lithium carbonate is precipitated from the purified brine by adding soda ash solution; the resultant solution is filtered to obtain solid lithium carbonate; an aqueous slurry of lithium carbonate is prepared in a reactor equipped with an inlet for introducing carbon dioxide gas into said aqueous slurry to form an aqueous lithium bicarbonate solution, said aqueous lithium bicarbonate solution is passed through filter and optionally through ion exchange column for further calcium and magnesium removal; said filtered lithium bicarbonate solution is introduced into a second reactor and adjusted to from 60 to 100° C. to precipitate ultra-pure lithium carbonate.
WO 2011/082444 A1 discloses a process for the production of lithium carbonate, the process comprises: calcining an alpha-spodumene ore or concentrate to produce beta-spodumene, sulphating at elevated temperature, passing the sulphated beta-spodumene to a leach step in which lithium sulphate is leached in water. The pregnant leach solution is passed to a series of impurity removal steps in which iron, alumina, silicates and magnesium are removed, adding sodium carbonate to the product for precipitating calcium, then ion exchanging for removing residual calcium, magnesium and other multivalent cations. The purified product is passed to lithium carbonate precipitation. The publication also discloses passing the precipitated lithium carbonate to a bicarbonate circuit, the bicarbonate circuit comprising digestion with carbon dioxide to produce bicarbonate intermediate and subsequent crystallisation to produce a lithium carbonate product.
Olivier, C. A and Nenninger, E. H, Continuous Process for the production of lithium carbonate, CIM Bulletin, July 1979, disclose a process for soda leaching of spodumene concentrate and carbonating under high pressure.
Galaxy Resources Limited has published a media release in November 2008 relating to preliminary test work to produce battery grade lithium carbonate using a ‘Soda Ash’ processing technique.